JP2006185103A - Pressure reducing valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure reducing valve that can precisely regulate pressure even in an environment involving sudden fluctuations in supply side gas pressure, by suppressing overtravel of a piston. <P>SOLUTION: The pressure reducing valve 1 ensures sealing property between a pressure reduction chamber 26 and a pressure regulation chamber 32 with a lip seal 37 arranged on an outer circumference 25a of the piston 25. An O ring 38 is arranged as an annular member on the outer circumference 25a of the piston 25, and the O ring 38 is brought into slide contact with an inner circumference 24a of a cylinder 24 to suppress overtravel of the piston 25. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pressure reducing valve used for pressure adjustment of a high pressure gas such as hydrogen gas for a fuel cell vehicle.

  In general, the pressure reducing valve (regulator) as described above includes an on-off valve provided between a primary port through which high-pressure gas flows and a secondary port on the external supply side. The pressure (primary pressure) of the high-pressure gas flowing in from the port is reduced (secondary pressure) and supplied to the outside.

Conventionally, such a pressure reducing valve is provided with a cylinder provided downstream of the on-off valve and a piston slidably provided in the cylinder and partitioning the pressure reducing chamber and the pressure adjusting chamber. There is a so-called piston type pressure reducing valve that opens and closes an opening / closing valve by movement of a piston according to a pressure difference between a chamber side and a pressure reducing chamber side (see, for example, Patent Document 1).
JP 2004-192462 A

  By the way, in such a piston type pressure reducing valve, normally, a sealing member (air tightness) between the pressure reducing chamber and the pressure adjusting chamber is secured by a sealing member disposed on the outer peripheral surface of the piston. In this case, an O-ring is used for the seal member.

  However, in recent years, hydrogen tanks used in fuel cell vehicles and the like have been further increased in pressure to increase their storage capacity (for example, 70 MPa), and the pressure reducing valve is also located on the pressure reducing chamber side of the piston. The gas pressure applied to the surface (pressure receiving surface) and the seal member is extremely high. For this reason, if an O-ring is used as a sealing member as in a normal pressure reducing valve to ensure sufficient sealing performance, the compression rate must be extremely high. There is a problem that the movement of the piston is hindered by an increase in the friction between them.

  Therefore, conventionally, in such a pressure reducing valve for high-pressure gas, an annular seal member provided with a sliding contact piece (seal lip) that comes into sliding contact with the inner peripheral surface of the cylinder by the pressing force of the elastic member, that is, a so-called lip seal is provided on the outer periphery of the piston. The sealing property is ensured by disposing on the surface.

  For example, in the pressure reducing valve 41 shown in FIG. 3, the lip seal 42 includes a resin ring member 43 having a U-shaped cross section, and a leaf spring 45 as an elastic member disposed in the recess 44 of the ring member 43. The lip seal 42 is inserted into a receiving groove 48 formed on the outer peripheral surface of the piston 46 and is fixed to the piston 46 by a fixing nut 49. The seal lip 47 of the ring member 43 is pressed toward the cylinder inner peripheral surface 50 by the elastic force of the leaf spring 45 and is brought into sliding contact with the cylinder inner peripheral surface 50, so that the space between the decompression chamber and the pressure adjustment chamber is reduced. It is designed to seal.

  As described above, by using the lip seal as the seal member, it is possible to move the piston while ensuring sufficient sealing performance even in high-pressure gas applications. However, since the seal lip is pressed against the inner circumferential surface of the cylinder with a high pressing force corresponding to the gas pressure, there is still room for improvement in the smoothness of movement when the piston moves. Especially in an environment where the use state, that is, the gas pressure on the supply side fluctuates sharply, such as a fuel cell vehicle, there is a problem that the amount of movement becomes excessive due to a sudden movement of the piston.

  The present invention has been made to solve the above problems, and its purpose is to suppress the excessive movement of the piston, and to perform highly accurate pressure adjustment even in an environment where the gas pressure on the supply side fluctuates sharply. An object of the present invention is to provide a pressure reducing valve capable of performing the above.

  In order to solve the above problems, an invention according to claim 1 is directed to an on-off valve provided between a primary port and a secondary port, a cylinder provided downstream of the on-off valve, The on-off valve is provided by partitioning the pressure reducing chamber and the pressure adjusting chamber and sliding in the cylinder according to a pressure difference between the pressure adjusting surface on the pressure adjusting chamber side and the pressure receiving surface on the pressure reducing chamber side. And a piston that opens and closes the piston, and an annular seal member having a sliding contact piece that is in sliding contact with the inner peripheral surface of the cylinder by the pressing force of the elastic member is disposed on the outer peripheral surface of the piston. The piston is disposed closer to the pressure adjusting chamber than the seal member on the outer circumferential surface of the piston, and the inner circumference of the cylinder is smaller than the pressing force for sliding the sliding contact piece on the inner circumferential surface of the cylinder. By sliding against the surface, the piston Further comprising suppressing annular member to move, and the gist.

  According to the above configuration, excessive energy that causes excessive movement of the piston can be consumed by friction between the inner peripheral surface of the cylinder and the annular member that is in sliding contact with the inner peripheral surface during the movement. As a result, excessive movement of the piston is suppressed, and high-precision pressure regulation can be performed even in an environment where the gas pressure on the supply side fluctuates sharply.

  Many of the pressure reducing valves are open to the atmosphere having a pressure adjusting chamber, a pressure adjusting chamber, and a through hole that communicates with the outside, and foreign matter enters from the through hole into the pressure adjusting chamber and thus between the piston and the cylinder. There is a case. In that respect, according to the above configuration, the annular member can prevent such foreign matter from reaching the seal member, and can prevent deterioration of the sealing performance of the seal member due to the foreign matter being caught.

The gist of the invention described in claim 2 is that the annular member is an O-ring.
According to the above configuration, the buffer member can be formed simply and inexpensively, and in addition, its assembly is easy.

The gist of the invention described in claim 3 is that the compression ratio of the annular member is 8 to 15%.
According to the above configuration, the annular member (O-ring) does not hinder the smooth movement of the piston, and the frictional force necessary for suppressing the excessive movement of the piston can be ensured.

  According to the present invention, it is possible to provide a pressure reducing valve capable of controlling pressure with high accuracy even in an environment in which excessive movement of the piston is suppressed and the gas pressure on the supply side changes steeply.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
As shown in FIG. 1, the pressure reducing valve 1 of the present embodiment is a pressure reducing valve (regulator) for a high-pressure hydrogen tank disposed in a plug body housing 2 that closes an opening of the hydrogen tank. Is configured to include a valve mechanism 3 formed in the plug housing 2 and an outer housing 5 that closes an opening of the plug housing 2.

  The plug housing 2 is formed with a first recess 6 and a second recess 7 deeper than the first recess 6 at the center of the first recess 6. An inflow channel 8 communicating with the inside of the hydrogen tank is formed on the side wall near the bottom surface 7 a of the second recess 7, and an outflow channel 9 communicating with the external supply port is formed on the bottom surface of the first recess 6. In this embodiment, the inflow passage 8 constitutes a primary port, and the outflow passage 9 constitutes a secondary port.

  A lid 13 formed in a cylindrical shape is fixed to the opening side end of the second recess 7, and a bottom body 14 is provided near the bottom of the second recess 7. A primary pressure chamber 15 is formed by the space between the bottom body 14 and the bottom surface 7 a of the second recess 7, and the valve chamber 16 is formed by the space between the lid 13 and the bottom body 14 in the second recess 7. It is configured.

  The bottom body 14 is formed with a through hole 17 that communicates the primary pressure chamber 15 and the valve chamber 16, and hydrogen gas that has flowed into the primary pressure chamber 15 from the inflow passage 8 passes through the through hole 17. It flows into the valve chamber 16. The inner peripheral surface of the lid 13 is partially reduced in diameter, and a small-diameter through hole 18 is formed at the center of the reduced diameter portion. A valve seat 19 is provided on the valve chamber 16 side of the through-hole 18, and a valve body 20 that is detachably accommodated with respect to the valve seat 19 is provided in the valve chamber 16. . In the present embodiment, the valve body 20 is urged toward the seating direction on the valve seat 19 by the elastic force of the valve spring 21. Then, when the valve body 20 is separated from the valve seat 19, the hydrogen gas in the valve chamber 16 flows out to the first recess 6 side through the through hole 18, and the outflow is blocked. It has become. In other words, in the present embodiment, the valve body 20 and the valve seat 19 constitute an on-off valve.

  On the other hand, the outer housing 5 is formed in a bottomed cylindrical shape, and a flange 23 extending outward in the radial direction is provided in the opening. The outer housing 5 is fixed to the opening end of the first recess 6 by the flange 23 being fastened to the outer side surface 2a of the plug body housing 2, thereby closing the opening.

  A cylinder 24 is formed in the opening in the outer housing 5, and a piston 25 is provided in the cylinder 24 so as to be slidable in the cylinder 24. The cylinder 24 is formed so as to be coaxial with the lid body 13. The piston 25 divides the inner space of the outer housing 5 and the first recess 6 closed by the outer housing 5.

  That is, in the present embodiment, the first recess 6 that is closed by the outer housing 5 and partitioned from the internal space of the outer housing 5 by the piston 25 constitutes the decompression chamber 26. The hydrogen gas in the valve chamber 16 flows into the decompression chamber 26 through the through-hole 18 formed in the lid body 13, and the outflow flow formed in the first recess 6 constituting the decompression chamber 26. It is supplied to the outside through a path 9.

  On the other hand, a coil spring 28 is disposed in the inner space of the outer housing 5 defined by the piston 25, and one end of the coil spring 28 is in contact with the piston 25. Further, a spring receiver 29 is fixed to the other end of the coil spring 28, and the tip of an adjustment screw 31 penetrating the bottom portion 30 of the outer housing 5 is brought into contact with the spring receiver 29. The piston 25 is urged toward the decompression chamber 26 side by the elastic force of the coil spring 28.

  That is, in this embodiment, the inner space of the outer housing 5 partitioned by the piston 25 constitutes the pressure adjustment chamber 32, and the surface of the piston 25 on the pressure adjustment chamber 32 side constitutes the pressure adjustment surface 33. The piston 25 slides in the cylinder 24 in accordance with the pressure difference between the pressure adjusting surface 33 and the surface of the piston 25 on the decompression chamber 26 side (pressure receiving surface 34).

  Further, a valve stem 35 inserted through the through hole 18 is fixed to the pressure receiving surface 34 of the piston 25, and the piston 25 is connected to the valve body 20 by the valve stem 35. In the present embodiment, the valve body 20 and the valve stem 35 are integrally formed. Then, the movement of the piston 25 is transmitted to the valve body 20 through the valve stem 35, so that the valve body 20 is detached from the valve seat 19 provided in the through hole 18, that is, the on-off valve is opened and closed. It has become.

  That is, the piston 25 is configured such that the gas pressure in the decompression chamber 26 (pressure on the pressure receiving surface 34) is set by operating the adjusting screw 31, and the pressure on the pressure adjusting chamber 32 side (the coil spring 28 presses the pressure adjusting surface 33. If the pressure is higher than the pressure to be adjusted, the pressure adjustment chamber 32 is moved. Thereby, the valve body 20 is seated (closed) on the valve seat 19, and the inflow of hydrogen gas from the valve chamber 16 to the decompression chamber 26 is blocked. When the gas pressure in the decompression chamber 26 is lower than the pressure on the pressure adjustment chamber 32 side, the piston 25 moves to the decompression chamber 26 side. As a result, the valve body 20 is separated (opened) from the valve seat 19, and hydrogen gas flows from the valve chamber 16 into the decompression chamber 26.

  In this way, the piston 25 slides according to the pressure difference between the pressure adjusting surface 33 and the pressure receiving surface 34, and the valve body 20 and the valve seat 19 constituting the opening / closing valve are separated from each other (opening / closing), whereby the decompression chamber 26. The gas pressure inside is balanced with the pressure on the pressure regulating chamber 32 side. Thereby, the pressure (secondary pressure) of the hydrogen gas supplied to the outside through the outflow passage 9 is set to a predetermined pressure set as the pressure on the pressure adjustment chamber 32 side from the primary pressure that is the pressure in the hydrogen tank. The pressure is reduced to the pressure.

(Piston overtravel suppression structure)
Next, a structure for suppressing excessive movement of the piston in the pressure reducing valve of the present embodiment will be described.
As shown in FIG. 2, in the pressure reducing valve 1 of the present embodiment, the sealing performance between the pressure reducing chamber 26 and the pressure adjusting chamber 32 is ensured by the lip seal 37 disposed on the outer peripheral surface 25 a of the piston 25. Yes. In addition, since the structure of the lip seal 37 of this embodiment and the arrangement | positioning structure to the piston 25 are the same as that of the said prior art example (refer FIG. 3), the description is abbreviate | omitted.

  However, as described above, when the lip seal 37 is used as the seal member of the piston 25 in the high pressure gas pressure reducing valve such as the pressure reducing valve 1 of the present embodiment, the seal lip 47 is inevitably disposed on the inner periphery of the cylinder 24. Since the pressing force pressed against the surface 24a is increased, the piston 25 starts to move with a delay with respect to the change in the differential pressure between the primary pressure and the secondary pressure, and the movement at the start of the movement becomes abrupt. This is a decrease due to the difference between the static friction force between the seal lip 47 and the inner peripheral surface 24a of the cylinder 24 before the movement of the piston 25 and the dynamic friction force between these members after the movement starts. That is, even if the secondary pressure decreases and the differential pressure from the primary pressure increases, the piston 25 does not start to move immediately because the coefficient of static friction between the seal lip 47 and the inner peripheral surface 24a of the cylinder 24 is large. When the differential pressure is further increased and the piston 25 starts to move, the frictional force between the seal lip 47 and the inner peripheral surface 24a of the cylinder 24 is switched to the dynamic frictional force, so that the piston 25 is instantaneously reduced. 25 moves rapidly. In particular, such as in a fuel cell vehicle, this tendency becomes remarkable in an environment where the use state, that is, the gas pressure on the supply side fluctuates rapidly due to a change in the demand amount (required driving force) of hydrogen gas, There exists a problem that the adjustment precision of gas pressure deteriorates.

  In consideration of this point, in the pressure reducing valve 1 of the present embodiment, an O-ring 38 as an annular member that suppresses excessive movement of the piston 25 is disposed on the outer peripheral surface 25a of the piston 25. As a result, when the piston 25 starts to move, in addition to the dynamic frictional force between the seal lip 47 and the inner peripheral surface 24a of the cylinder 24, the frictional force between the O-ring 38 and the inner peripheral surface 24a of the cylinder 24 is abrupt. Since it acts so as to suppress movement, excessive movement of the piston 25 is suppressed.

  More specifically, the O-ring 38 is accommodated in the accommodating groove 39 formed on the outer peripheral surface 25a of the piston 25, so that the O-ring 38 is disposed closer to the pressure adjusting chamber 32 than the lip seal 37 on the outer peripheral surface 25a. Yes.

  The O-ring 38 of the present embodiment is formed of an elastic material such as rubber or elastomer, similar to that used as a seal member, but its compression rate (inside the housing groove 39 by the inner peripheral surface 24a of the cylinder 24). The compression ratio) is set lower than the compression rate of the seal member used. Specifically, the compression rate of what is usually used as a sealing member is about 25 to 30%, whereas the compression rate of the O-ring 38 of the present embodiment is about 15% at maximum (preferably about 12%). ) Is set. When the compression rate exceeds 15%, the pressing force with which the O-ring 38 is pressed against the inner peripheral surface 24a increases, and the contact area with the inner peripheral surface 24a also increases. For this reason, the static frictional force acting on the O-ring 38 increases, and the fluctuation of the frictional force of the O-ring 38 when the piston 25 starts to move increases. Therefore, the excessive movement of the piston 25 cannot be suppressed appropriately. Further, the compression ratio to be ensured in order to make the O-ring 38 slidably contact with the inner peripheral surface 24a of the cylinder 24 is about 8%. This is because if the compression ratio is less than 8%, the frictional force necessary to suppress the excessive movement of the piston cannot be exhibited. Here, the compression rate is a quotient obtained by dividing the decrease in the thickness of the O-ring by the thickness before compression of the O-ring, and corresponds to the compression strain rate or crushing rate. The elastic pressure of the O-ring 38, in other words, the force with which the O-ring 38 presses the inner peripheral surface 24 a of the cylinder 24 is set to be lower than the elastic force of the leaf spring 45 as an elastic member in the lip seal 37.

  Now, the excessive movement of the piston 25 in question causes the piston 25 to be delayed for a moment because the elastic force of the leaf spring 45 presses the seal lip 47 as a sliding contact piece against the inner peripheral surface 24a of the cylinder 24 with high pressure. This is a phenomenon that occurs when energy (pressure difference between the pressure adjustment surface 33 and the pressure receiving surface 34) is accumulated due to the delay. Therefore, it is possible to suppress the excessive movement by consuming excessive energy given by the delay when the piston 25 moves.

  Therefore, in the pressure reducing valve 1 of the present embodiment, the O-ring 38 is disposed on the outer peripheral surface 25a of the piston 25, and the piston 25 moves by sliding the O-ring 38 against the inner peripheral surface 24a of the cylinder 24. In this case, excessive energy that causes excessive movement of the piston 25 due to the friction is consumed. Thus, excessive movement of the piston 25 is suppressed, and high-precision pressure adjustment can be performed even in an environment where the supply-side gas pressure fluctuates sharply.

As described above, according to the present embodiment, the following features can be obtained.
(1) The pressure reducing valve 1 ensures the sealing performance between the pressure reducing chamber 26 and the pressure adjusting chamber 32 by a lip seal 37 disposed on the outer peripheral surface 25 a of the piston 25. An O-ring 38 as an annular member is disposed on the outer peripheral surface 25 a of the piston 25, and the O-ring 38 is brought into sliding contact with the inner peripheral surface 24 a of the cylinder 24.

  With such a configuration, excess energy that causes excessive movement of the piston 25 is consumed by the frictional force of the O-ring 38 that is in sliding contact with the inner peripheral surface 24a of the cylinder 24 when the piston 25 moves. Can do. As a result, excessive movement of the piston 25 is suppressed, and high-precision pressure adjustment can be performed even in an environment where the supply-side gas pressure fluctuates sharply.

  (2) The elastic force with which the O-ring 38 presses the inner peripheral surface 24 a of the cylinder 24 is set lower than the elastic force of the leaf spring 45 in the lip seal 37. With such a configuration, movement of the piston 25 is not hindered.

(3) The O-ring 38 is disposed closer to the pressure adjustment chamber 32 than the lip seal 37.
Many pressure reducing valves are not limited to the pressure reducing valve 1 of the present embodiment, and many of the pressure reducing valves are open to the atmosphere having a pressure adjusting chamber 32, a through hole 40 (see FIG. 1) that communicates the pressure adjusting chamber 32 and the outside. In some cases, foreign matter may enter the pressure adjusting chamber 32 from the through-hole 40 and thus between the piston 25 and the cylinder 24. In this respect, the O-ring 38 prevents such foreign matter from reaching the lip seal 37 and prevents the sealing performance of the lip seal 37 from being lowered due to the foreign matter being caught.

In addition, you may change each said embodiment as follows.
In this embodiment, the O-ring 38 is disposed as the annular member on the outer peripheral surface 25a of the piston 25. However, the excessive energy that causes excessive movement when the piston 25 moves is effectively consumed. In this case, a configuration other than the O-ring 38 may be used. For example, instead of the O-ring 38, a member that is in sliding contact with the inner peripheral surface 24a of the cylinder 24 may be formed of a material other than the elastic material, and this may be an annular member.

  In the present embodiment, the present invention is embodied in a pressure reducing valve (regulator) for a high pressure hydrogen tank disposed in the plug body housing 2 of the hydrogen tank, but the pressure reducing valve installed separately from the plug body housing 2 It may be embodied in. The gas stored in the tank is not limited to hydrogen, but may be oxygen, CNG (compressed natural gas), LP gas, or the like.

Sectional drawing of the pressure-reduction valve of this embodiment. The fragmentary sectional view of the piston vicinity in the pressure reducing valve of this embodiment. The fragmentary sectional view of the piston vicinity in the pressure reducing valve of the conventional example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Pressure reducing valve, 8 ... Inflow flow path, 9 ... Outflow flow path, 16 ... Valve chamber, 19 ... Valve seat, 20 ... Valve body, 24 ... Cylinder, 24a ... Inner peripheral surface, 25 ... Piston, 25a ... Outer peripheral surface , 26 ... decompression chamber, 32 ... pressure adjustment chamber, 33 ... pressure adjustment surface, 34 ... pressure receiving surface, 35 ... valve stem, 37 ... lip seal, 38 ... O-ring, 45 ... leaf spring, 47 ... seal lip.

Claims (3)

An on-off valve provided between the primary port and the secondary port, a cylinder provided downstream of the on-off valve, a decompression chamber and a pressure adjustment chamber provided in the cylinder, and the pressure adjustment chamber A piston that opens and closes the on-off valve by sliding in the cylinder according to a pressure difference between the pressure adjusting surface on the side and the pressure receiving surface on the decompression chamber side, and an elastic member is provided on the outer peripheral surface of the piston A pressure reducing valve provided with an annular seal member provided with a sliding contact piece that is in sliding contact with the inner peripheral surface of the cylinder by a pressing force of
The piston is disposed closer to the pressure adjusting chamber than the seal member on the outer peripheral surface of the piston, and is applied to the inner peripheral surface of the cylinder with a smaller elastic force than the pressing force for sliding the sliding contact piece on the inner peripheral surface of the cylinder. An annular member that suppresses excessive movement of the piston by sliding contact;
A pressure reducing valve. The pressure reducing valve according to claim 1,
The pressure reducing valve characterized in that the annular member is an O-ring. The pressure reducing valve according to claim 1 or 2,
The pressure reducing valve characterized in that the compression rate of the annular member is 8 to 15%.

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